The invention relates generally to articles made from nickel-based superalloys, and methods for making such articles. More particularly, the invention relates to additively manufactured articles fabricated using nickel-based superalloys, and methods for making such articles.
Ni-base superalloys are very useful alloys that can exhibit substantial creep and oxidation resistances at high temperatures, often in excess of 0.7 of their absolute melting temperatures. One form of high-temperature nickel base alloy of particular interest is a cast form, designed for desired creep and environmental properties, such as for example, oxidation resistance and hot corrosion resistance. One of the nickel base superalloy compositions that is widely used, especially in gas turbine components used in hot gas path applications, is known by the trade name “Rene 108,” a trademark of the General Electric Company.
Additive manufacturing is a suite of emerging technologies that fabricate three-dimensional objects directly from digital models through an additive process, typically by depositing material layer upon layer and joining successive layers in place. Unlike traditional manufacturing processes involving subtraction (e.g., cutting and shearing) and forming (e.g., stamping, bending, and molding), additive manufacturing joins materials together to build products.
Certain components, such as for example, turbine engine hot-gas-path components made from nickel-base superalloys can benefit from the design flexibility enabled by the use of additive manufacturing techniques. However, superalloys tend to include a large number of alloying elements, resulting in a somewhat complicated physical metallurgy that can be sensitive to how the material is thermally and mechanically processed; These materials often present a challenge when employed in additive manufacturing methods because the rapid heating and cooling involved in these processes often result in sub-optimal alloy microstructure and material properties Therefore, it is desirable to design a nickel-base superalloy composition that can be employed in additive manufacturing methods to fabricate items having properties that are similar to their cast counterparts.